A series of Ni,Sn and Ca modified Pd/TiO2-Al2O3catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOxby H2was evaluated.The results showed that the NOxconversion and N2selectivity were improved over Pd-Sn/TiO2-Al2O3and Pd-Ni/TiO2-Al2O3catalysts above 200°C.More importantly,the N2selectivity and high-temperature activity of Pd-Sn/TiO2-Al2O3catalyst was far superior to the single Pd/TiO2-Al2O3catalyst.The optimal Sn loading was 2 wt.%.X-ray diffraction(XRD)results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3.Temperature-programmed reduction(H2-TPR)results demonstrated that the addition of Sn contributes to the formation of Pd0and improving the redox property of Pd/TiO2-Al2O3.The additives of Ni and Sn also facilitated the absorption of NOxand the oxidation of NO to NO2,which play important roles in the selective catalytic reduction of NOxby hydrogen. A series of Ni, Sn and Ca modified Pd / TiO2-Al2O3catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOxby H2was evaluated. The results showed that NOxconversion and N2selectivity were improved over Pd-Sn / TiO2-Al2O3 and Pd-Ni / TiO2-Al2O3catalysts above 200 ° C. Importantly, the N2selectivity and high-temperature activity of Pd-Sn / TiO2- Al2O3catalyst was far superior to the single Pd / TiO2- Al2O3catalyst. was 2 wt.% X-ray diffraction (XRD) results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO 2 -Al 2 O 3 .Temperature-programmed reduction (H2-TPR) results demonstrated that the addition of Sn contributes to the formation of Pd0 and improving the redox property of Pd / TiO2-Al2O3. The additives of Ni and Sn also facilitated the absorption of NOx and the oxidation of NO to NO2, which play important roles in the selective catalytic reduction of NOx by hydrogen.